NEW YORK - Former Vice President Joe Biden leads all other candidates for the 2020 Democratic presidential nomination and draws his strongest levels of support from minorities and older adults, according to a Reuters/Ipsos public poll released on Wednesday.

The April 17-23 poll focused on the vote preferences of 2,237 Democrats and independents the two groups that may select the Democratic nominee in most of the statewide contests ahead of the 2020 general election.

According to the poll, 24 percent would vote for Biden over 19 other declared and potential candidates.

Another 15 percent said they would support U.S. Senator Bernie Sanders of Vermont, who ran a competitive campaign for the Democratic nomination in 2016.

No other candidate received more than 7 percent of public support, and 21 percent said they 'don't know' which candidate they would back in a primary.

The poll measures how potential voters feel right now. Many may change their minds as they become better acquainted with the candidates. It has a credibility interval, a measure of precision, of 2 percentage points for the combined group of Democrats and independents.

The statewide nominating contests will kick off in early February next year, led by Iowa.

Biden, 76, who has sought the Democratic presidential nomination twice before and is expected to announce a third run later this week, remains widely popular since he left the White House in 2016 after two terms as vice president.

Sixty-three percent of all Americans say they have a 'favorable' impression of Biden, including 88 percent of Democrats, 59 percent of independents and 39 percent of Republicans.

In comparison, 58 percent of Americans said they have a favorable view of Sanders and Pete Buttigieg, the 37-year-old mayor of South Bend, Indiana, whose upstart campaign has out-raised some of his more established rivals this year.

All three appear to have stronger bi-partisan appeal than President Donald Trump. According to the poll, 44 percent of all adults said they have a generally favorable view of Trump.

Biden receives his strongest levels of support from older adults and minorities.

Thirty-two percent of adults who are 55 years old and older said they would vote for Biden over other candidates. And 30 percent of non-white adults, including about 4 in 10 African-Americans, said they would back Biden for the nomination.

The poll shows that at this early stage of the presidential campaign, Americans say they will vote for candidates who have been in the national spotlight for a long time.

Their preferences may change once they get to know other candidates for the nomination.

More than 80 percent of Democrats said they were at least 'somewhat familiar' with Biden and Sanders.

Sixty-seven percent of Democrats were familiar with Senator Elizabeth Warren of Massachusetts, and about half said they were familiar with former U.S. Representative Beto O'Rourke of Texas or U.S. Senators Kamala Harris of California and Cory Booker of New Jersey.

The rest of the field appears to be largely unknown by a majority of Democrats.

The Reuters/Ipsos poll was conducted online in English throughout the United States. It gathered responses from 4,018 adults in all, including 1,449 Democrats, 1,437 Republicans and 788 independents.